SAN DIEGO -- Anthony Rizzo was back in San Diego, so he hit the beach.

Rizzo hit a go-ahead, two-run home run into the sandy play area beyond the fence in right-center at Petco Park against his old team and the Chicago Cubs beat the punchless San Diego Padres 5-1 Thursday night. Rizzo's shot helped back Jake Arrieta, who pitched six strong innings.

The left-handed Rizzo put the Cubs ahead 2-1 in the fourth with a 417-foot homer to center on a 3-1 fastball from lefty Eric Stults. It was his eighth.

"If you hit a ball well, if you get it, you're going to get it here," said Rizzo, who made his big league debut with San Diego in 2011. "But it's nice not having to take batting practice here every day."

Rizzo hit just .141 with one homer and nine RBIs in two stints with the Padres in 2011 before being traded to the Cubs in the deal that sent right-hander Andrew Cashner to San Diego.

Rizzo is hitting .275 this season.

"That ball went to the beach," said Cubs first-year manager Rick Renteria, who spent the past six seasons on San Diego's coaching staff.

Stults said Rizzo homered on a fastball down the middle.

"If I execute the pitch down and away, the worse thing is he probably hits a single," Stults said. "But it was 3-1, nobody out, and I didn't want to put him on base."

Rizzo also had a double.

"He had some good at-bats," Renteria said. "His approach is pretty solid."

Arrieta (1-0) held San Diego to one run and four hits, struck out seven and walked one. He was activated May 3 after beginning the season on the disabled list with tightness in his right shoulder. He lowered his ERA to 2.33. Carlos Villanueva pitched the final three innings for his first save this season.

"Jake did a nice job," Renteria said. "He pushed himself through six and allowed us to get to Villa and he did the rest."

San Diego lost its fourth straight game. It was the 15th time in 48 games the Padres scored one or no runs. The Padres were shut out for the eighth time -- most in the majors -- on Wednesday night, losing 2-0 to Minnesota.

Padres bench coach Dave Roberts filled in for manager Bud Black, who was at his daughter's college graduation.

"It was good to see Rick on the other side," Roberts said. "He seemed in good spirits. Just a year ago, we were together. We shared the same locker room. But at 7:10 we were ready to win a baseball game."

Junior Lake was aboard on a bunt single down the third-base line, the Cubs' first hit of the night off Stults.

The Cubs chased Stults in the fifth with three runs and four hits. Nate Schierholtz hit a leadoff double and scored on Darwin Barney's single to center. Arrieta sacrificed Barney, who scored on Emilio Bonifacio's single to right. Lake doubled over center fielder Cameron Maybin's head to bring in Bonifacio.

San Diego's only run came on Seth Smith's two-out homer to right in the first, his team-leading sixth.

Stults (2-5) gave up five runs and six hits in 4 2/3 innings, struck out four and walked none.

The Padres wore replica uniforms from 1984, when they beat the Cubs in the NL championship series to reach the World Series for the first time.

Game notes
The four-game series continues Friday night when Cubs RHP Edwin Jackson (3-3, 3.98) faces Padres RHP Tim Stauffer (1-0, 2.41), who will be making his first start of the season. ... Padres LHP Robbie Erlin, who had been scheduled to start Friday night, went on the 15-day disabled list with a sore left elbow, retroactive to Sunday. He is 3-4 with a 4.53 ERA in nine appearances, including eight starts. To take his spot on the roster, the Padres selected RHP Blaine Boyer from Triple-A El Paso.